Some comments concerning the blow-up of solutions of the exponential reaction-diffusion equation

TL;DR

This paper refines understanding of blow-up behavior in exponential reaction-diffusion equations, showing solutions become immediately regular after blow-up without symmetry restrictions and analyzing blow-up rates in 2D.

Contribution

It demonstrates immediate regularization post-blow-up without radial symmetry and establishes conditions for self-similar behavior and Type I blow-up in 2D.

Findings

Solutions become regular immediately after blow-up.

No symmetry assumptions are needed for regularization.

Blow-up in 2D is of Type I at the origin.

Abstract

The aim of this paper is to refine some results concerning the blow-up of solutions of the exponential reaction-diffusion equation. We consider solutions that blow-up in finite time, but continue to exist as weak solutions beyond the blow-up time. The main result is that these solutions become regular immediately after the blow-up time. This result improves on that of Fila, Matano and Pol\'acik, who consider radially nonincreasing solutions, whereas no such assumption is needed here. Under certain additional assumptions we also obtain that the regularization is asymptotically selfsimilar. Moreover, we consider the question of blow-up rate for radial solutions of the two-dimensional problem and prove that the blow-up is of type I, provided that the maximum of the solution is attained at the origin.